Publication:

Wideband unidirectional transmission with tunable sign-switchable refraction and deflection in nonsymmetric structures

A general theory of reciprocal unidirectional transmission with tunable sign-switchable refraction and deflection of outgoing wave in structures with broken spatial inversion symmetry is presented. Several coupling scenarios connected with the diffraction-inspired asymmetry in transmission are considered for volumetric structures with one-side corrugations. They illustrate conditions of coexistence of diodelike unidirectional transmission and tunability of deflection and refraction, including change of their sign. Simulation results are presented and analyzed for nonsymmetric structures based on the stacked subwavelength hole array metamaterial. It is shown that one-way coupling can appear within a wide range of frequencies and angles of incidence, a part of which may be used to obtain different signs of deflection. Transmission results and field distributions confirm the possibility of obtaining high-contrast unidirectional transmission that can be tuned by varying incidence angle, while frequency is fixed. A pronounced unidirectional transmission is demonstrated at negative deflection in structures that are only 0.47λ0 thick, whereas a thicker structure is required in order to obtain both signs of deflection in a unidirectional regime.